Engineers at the University of Illinois Chicago have built a cost-effective artificial leaf that can capture carbon dioxide at rates 100 times better than current systems. Unlike other carbon capture systems, which work in labs with pure carbon dioxide from pressurized tanks, this artificial leaf works in the real world. It captures carbon dioxide from more diluted sources, like air and flue gas produced by coal-fired power plants, and releases it for use as fuel and other materials.
[..]
Illustration of a carbon capture process designed by UIC College of Engineering scientists. Carbon dioxide from air or flue gas is absorbed by a dry organic solution to form bicarbonate ions, which migrate across a membrane and are dissolved in a liquid solution to concentrated CO2. Carbon atoms are shown in red, oxygen atoms are shown in blue and hydrogen atoms are shown in white. (Credit: Aditya Prajapati/UIC)
Using a previously reported theoretical concept, the scientists modified a standard artificial leaf system with inexpensive materials to include a water gradient — a dry side and a wet side — across an electrically charged membrane.
On the dry side, an organic solvent attaches to available carbon dioxide to produce a concentration of bicarbonate, or baking soda, on the membrane. As bicarbonate builds, these negatively charged ions are pulled across the membrane toward a positively charged electrode in a water-based solution on the membrane’s wet side. The liquid solution dissolves the bicarbonate back into carbon dioxide, so it can be released and harnessed for fuel or other uses.
The electrical charge is used to speed up the transfer of bicarbonate across the membrane.
When they tested the system, which is small enough to fit in a backpack, the UIC scientists found that it had a very high flux — a rate of carbon capture compared with the surface area required for the reactions — of 3.3 millimoles per hour per 4 square centimeters. This is more than 100 times better than other systems, even though only a moderate amount of electricity (0.4 KJ/hour) was needed to power the reaction, less than the amount of energy needed for a 1 watt LED lightbulb. They calculated the cost at $145 per ton of carbon dioxide, which is in line with recommendations from the Department of Energy that cost should not exceed around $200 per ton.
